Luminescent taggant compositions, luminescent materials that include luminescent taggants, and articles including luminescent taggants are provided herein. In an embodiment, a luminescent taggant composition includes a first luminescent taggant, a second luminescent taggant, and a third luminescent taggant. The first luminescent taggant includes a first emitting ion that produces a first emission in a first taggant emission band when exposed to excitation energy. The second luminescent taggant includes a second emitting ion that is different from the first emitting ion and that produces a second emission in a second taggant emission band that is different from the first taggant emission band when exposed to excitation energy. The first luminescent taggant is substantially free of the second emitting ion and the second luminescent taggant is substantially free of the first emitting ion. The third luminescent taggant includes the first emitting ion and the second emitting ion.

A cold storage material of an embodiment includes a rare earth oxysulfide containing a rare earth element, a garnet-type rare earth oxide containing a rare earth element and Al, and an aluminum oxide, and a ratio of X-ray diffraction peak intensity of the garnet-type rare earth oxide to X-ray diffraction peak intensity of the rare earth oxysulfide is 0.1% or more and 40% or less.

A cold storage material of an embodiment includes a rare earth oxysulfide containing a rare earth element, a garnet-type rare earth oxide containing a rare earth element and Al, and an aluminum oxide, and a ratio of X-ray diffraction peak intensity of the garnet-type rare earth oxide to X-ray diffraction peak intensity of the rare earth oxysulfide is 0.1% or more and 40% or less.

A production method of rare earth oxysulfide comprising a step of mixing a rare earth compound with sulfuric acid and/or sulfate in such a proportion that sulfate ions are 0.75-1.75 mol to 1 mol of a rare earth element, thereby preparing a reaction solution to obtain a product; a step of calcining the product to obtain calcined powder; and a step of reducing the calcined powder to obtain rare earth oxysulfide.

Provided is a magneto-optical material which does not absorb fiber laser light in a wavelength range of 0.9-1.1 m and does not cause a thermal lens, while having a larger Verdet constant than TGG crystals, and which is suitable for constituting a magneto-optical device such as an optical isolator. This magneto-optical material is formed of a single crystal of a rare earth oxysulfide that is represented by formula (1) or a transparent ceramic which contains, as a main component, a rare earth oxysulfide that is represented by formula (1), and this magneto-optical material has a Verdet constant of 0.14 min/(Oe.Math.cm) or more at the wavelength of 1,064 nm.
(Tb.sub.xR.sub.1-x).sub.2O.sub.2S(1)
(In the formula, x is 0.3 or more but less than 1; and R represents at least one rare earth element that is selected from the group consisting of yttrium, lutetium, gadolinium, holmium, scandium, ytterbium, europium and dysprosium.)

A host lattice modified GOS scintillating material and a method for using a host lattice modified GOS scintillating material is provided. The host lattice modified GOS scintillating material has a shorter afterglow than conventional GOS scintillating material. In addition, a radiation detector and an imaging device incorporating a host lattice modified GOS scintillating material are provided. A spectral filter may be used in conjunction with the GOS scintillating material.

A cold storage material having a large thermal capacity in a ultra-low temperature range of 10 K or less and being highly durable against thermal shock and mechanical vibration. The cold storage material contains a rare earth oxysulfide ceramic represented by the general formula R.sub.2O.sub.2S in which R is one or more kinds of rare earth elements selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, and Al.sub.2O.sub.3 having a specific surface area of 0.3 m.sup.2/g to 11 m.sup.2/g is added to the cold storage material.

A cold storage material having a large thermal capacity in a ultra-low temperature range of 10 K or less and being highly durable against thermal shock and mechanical vibration. The cold storage material contains a rare earth oxysulfide ceramic represented by the general formula R.sub.2O.sub.2S in which R is one or more kinds of rare earth elements selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, and Al.sub.2O.sub.3 having a specific surface area of 0.3 m.sup.2/g to 11 m.sup.2/g is added to the cold storage material.

A ceramic scintillator of an embodiment includes a sintered body of a gadolinium oxysulfide phosphor containing praseodymium as a main activator. When a body color of the sintered body is represented by chromaticity coordinates (x, y) based on a CIE1931 chromaticity value, the sintered body has a body color satisfying 0.4x0.505 . . . (1) and 0.83x+0.075y0.83x+0.095 . . . (2). The ceramic scintillator of the embodiment is obtained by a method for manufacturing a ceramic scintillator, the method including a heat treatment step of causing a reaction gas containing oxygen and sulfur to react with the sintered body. A heat treatment time in the heat treatment step is 1 hour or more and 50 hours or less.

A ceramic scintillator of an embodiment includes a sintered body of a gadolinium oxysulfide phosphor containing praseodymium as a main activator. When a body color of the sintered body is represented by chromaticity coordinates (x, y) based on a CIE1931 chromaticity value, the sintered body has a body color satisfying 0.4x0.505 . . . (1) and 0.83x+0.075y0.83x+0.095 . . . (2). The ceramic scintillator of the embodiment is obtained by a method for manufacturing a ceramic scintillator, the method including a heat treatment step of causing a reaction gas containing oxygen and sulfur to react with the sintered body. A heat treatment time in the heat treatment step is 1 hour or more and 50 hours or less.